1. Field of the Invention
This invention relates to a preloaded annular seal for combustion apparatus, especially adapted for use in a liquid propellant gun. The invention herein described was made in the course of or under a contract with the Department of the Navy.
2. Prior Art
This invention is an improvement on the annular breech seal disclosed and claimed in my earlier patent, U.S. Pat. No. 3,783,737, issued Jan. 8, 1974. A liquid propellant gun which is well adapted to utilize the seal of the present invention is shown in U.S. Pat. No. 3,763,739, issued Oct. 9, 1973, to D. P. Tassie, to which reference may be had for details of the total system not herein shown.
High pressure resisting seals with an L-shape cross-section were disclosed in U.S. Pat. No. 3,783,737 as mounted on the bolt head, and preseated against the wall of the chamber by plastic deformation effected as the gun bolt was rammed into the firing position. These seals work well under the now normal chamber pressures of 50,000 to 60,000 psi. However, higher chamber pressures have been encountered. Under these higher pressures, the chamber elastically expands to provide a larger opening than normal, which permits the annular seal to expand to that larger opening which results in a plastic yielding of the seal. The seal, under these circumstances, develops a permanent enlargement and is then too tight against the chamber wall to be extracted by and with the bolt after firing.